/Engine/Plugins/MovieScene/MovieRenderPipeline/Source/MovieRenderPipelineCore/Public/Graph/MovieGraphDataTypes.h
Movie Graph Pipeline is mostly interested in knowing about ranges of time that it should render, and less concerned with the specifics of where that data comes from (ie: a Level Sequence). This lets you synchronize with a different data source to provide the ranges of time to render, and then theUMovieGraphTimeStepBaseclass figures out how to move around within that time step, before calling some functions to synchronize your external data source to actually match the evaluated time.
[UCLASS](Programming/UnrealArchitecture/Reference/Classes#classdeclaration)(BlueprintType, Abstract) class UMovieGraphDataSourceBase : public [UObject](API\Runtime\CoreUObject\UObject\UObject)